Back side illumination image sensors having an infrared filter

ABSTRACT

Back side illumination (BSI) image sensors are provided. A BSI image sensor includes a substrate and a plurality of pixels configured to generate electrical signals responsive to light incident on the substrate. Each of the plurality of pixels includes a photodiode, an infrared radiation (IR) cut-off filter above the photodiode, a light shield pattern above the photodiode and including an opening corresponding to an area of 1 to 15% of each of the plurality of pixels, a planarization layer on the light shield pattern, and a lens on the planarization layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of and claims priorityfrom U.S. patent application Ser. No. 16/433,515, filed on Jun. 6, 2019,which claims priority from Korean Patent Application No.10-2018-0165935, filed on Dec. 20, 2018, the disclosures of which arehereby incorporated herein by reference in entirety.

BACKGROUND

The present disclosure relates to back side illumination (BSI) imagesensors. An image sensor is a device for converting light into anelectrical signal. Recently, with the development of computer andcommunication industries, image sensors having improved performance aredesirable in various fields including camcorders, game machines, digitalcameras, display devices, mobile phones (e.g., smart phones), and thelike. Conventionally, front side illumination (FSI) image sensors aremainly used. The FSI image sensors have disadvantages in that lightreception efficiency is degraded because lines are disposed onphotodiodes. Recently, back side illumination (BSI) image sensors havebeen developed for reducing the disadvantages of such FSI image sensors.

SUMMARY

Some example embodiments of the inventive concepts are directed toproviding a back side illumination (BSI) image sensor embedding aninfrared rays/radiation (IR) cut-off filter.

In addition, some example embodiments of the inventive concepts aredirected to providing a BSI image sensor module of which manufacturingefficiency is improved by embedding an IR cut-off filter inside an imagesensor.

Further, some example embodiments of the inventive concepts are directedto providing a BSI image sensor module of which a thickness and amanufacturing cost are reduced by embedding an IR cut-off filter into animage sensor.

Furthermore, some example embodiments of the inventive concepts aredirected to providing an electronic device including a BSI image sensorwith an IR cut-off filter.

Additionally, some example embodiments of the inventive concepts aredirected to providing an electronic device including an image sensor ofwhich a thickness is reduced.

According to example embodiments, there is provided a BSI image sensorincluding a substrate and a plurality of pixels configured to generateelectrical signals responsive to light incident on the substrate. Eachof the plurality of pixels may include a photodiode, a device isolationregion around the photodiode, a dark current suppression layer above thephotodiode, an infrared radiation (IR) cut-off filter above thephotodiode, a light shield pattern above the photodiode and including anopening corresponding to an area of 1 to 15% of each of the plurality ofpixels, a light cut-off filter layer on the light shield pattern exceptfor the opening, a planarization layer on the light cut-off filterlayer, and a lens on the planarization layer.

According to example embodiments, there is provided a BSI image sensorincluding a substrate and a plurality of pixels configured to generateelectrical signals responsive to light incident on a back side of thesubstrate. Each of the plurality of pixels may include a photodiode, adark current suppression layer above the photodiode and including astack of a plurality of layers that each have a negative charge, aninfrared radiation (IR) cut-off filter above the photodiode andincluding a stack of a plurality of refractive index films, a lightshield pattern above the photodiode and including an openingcorresponding to an area of 1 to 15% of each of the plurality of pixels,a planarization layer on the light shield pattern, and a lens on theplanarization layer.

According to example embodiments, there is provided a BSI image sensorincluding a substrate and a plurality of pixels configured to generateelectrical signals responsive to light incident on a back side of thesubstrate. The BSI image sensor may include a plurality of readoutcircuits configured to readout the electrical signals of the pluralityof pixels. Moreover, each of the plurality of pixels may include aphotodiode, an infrared radiation (IR) cut-off filter above thephotodiode, a light shield pattern above the photodiode and including anopening corresponding to an area of 1 to 15% of each of the plurality ofpixels, a planarization layer on the light shield pattern, and a lens onthe planarization layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an electronic device including an imagesensor with an IR cut-off filter according to some example embodimentsof the inventive concepts.

FIG. 2A is a diagram illustrating the image sensor according to someexample embodiments of the inventive concepts.

FIG. 2B is a circuit diagram of a unit pixel constituting the pixelarray.

FIG. 3A shows a pixel of an image sensor according to some exampleembodiments of the inventive concepts and is a diagram illustrating anIR cut-off filter disposed on a light shield grid.

FIG. 3B is a diagram illustrating a dark current suppression layerdisposed in the pixel shown in FIG. 3A.

FIG. 3C is a diagram illustrating the device isolation portion and thedark current suppression layer in detail.

FIGS. 4A to 4D are diagrams illustrating examples in which a highrefractive index film and a low refractive index film are stacked toform the IR cut-off filter.

FIGS. 5A and 5B are diagrams illustrating a light shield grid of theimage sensor of the inventive concept.

FIG. 6A is a diagram illustrating an IR cut-off filter disposed belowthe light shield grid according to some example embodiments of theinventive concepts.

FIG. 6B is a diagram illustrating the dark current suppression layerdisposed in the pixel shown in FIG. 6A.

FIG. 7A is a diagram illustrating the IR cut-off filter disposed on thelight shield grid and a light cut-off filter layer disposed on the IRcut-off filter according to some example embodiments of the inventiveconcepts.

FIG. 7B is a diagram illustrating the dark current suppression layerdisposed in the pixel shown in FIG. 7A.

FIG. 8A is a diagram illustrating the light cut-off filter layerdisposed on the light shield grid and the IR cut-off filter is disposedbelow the light shield grid according to some example embodiments of theinventive concepts.

FIG. 8B is a diagram illustrating the dark current suppression layerdisposed in the pixel shown in FIG. 8A.

FIG. 9A is a diagram illustrating the IR cut-off filter disposed at acentral portion of the planarization layer according to some exampleembodiments of the inventive concepts.

FIG. 9B is a diagram illustrating the dark current suppression layerdisposed in the pixel shown in FIG. 9A.

FIG. 10A is a diagram illustrating the IR cut-off filter disposed on theplanarization layer according to some example embodiments of theinventive concepts.

FIG. 10B is a diagram illustrating the dark current suppression layerdisposed in the pixel shown in FIG. 10A.

FIG. 11A is a diagram illustrating the IR cut-off filter disposed on thelens according to some example embodiments of the inventive concepts.

FIG. 11B is a diagram illustrating the dark current suppression layerdisposed in the pixel shown in FIG. 11A.

FIG. 12 is a diagram showing image degradation by comparing a case inwhich an IR cut-off filter is embedded in an image sensor with a case inwhich the IR cut-off filter is not applied to the image sensor.

DETAILED DESCRIPTION

Hereinafter, an image sensor with an infrared rays/radiation (IR)cut-off filter and an electronic device including the same according toexample embodiments of the inventive concept will be described withreference to the accompanying drawings.

FIG. 1 is a diagram illustrating an electronic device including an imagesensor with an IR cut-off filter according to some example embodimentsof the inventive concepts. FIG. 2A is a diagram illustrating the imagesensor according to some example embodiments of the inventive concepts.

Referring to FIGS. 1 and 2A, an electronic device 10 according to someexample embodiments of the inventive concepts may include an imagesensor 100 having an IR cut-off filter and a display module 200. Thedisplay module 200 for displaying an image may be disposed in an upperportion of the electronic device 10, and the image sensor 100 may bedisposed below the display module 200. The display module 200 mayinclude an organic light emitting diode (OLED) panel 210 as a displaypanel for displaying an image. The display module 200 may include atouch panel 220 for sensing a user's touch. The touch panel 220 may bedisposed on the OLED panel 210. The display module 200 may include aprotection film 230 disposed on the touch panel 220 and a cushion part240 for cushioning an impact applied when a user touches.

The OLED panel 210 is configured to display an image on the basis of aninput image signal and may display the image through self-emissionwithout a backlight. The OLED panel 210 does not require a backlight,and therefore a thickness of the OLED panel 210 can be small. The touchpanel 220 may use sensors provided on a surface of the touch panel 220to detect a touch input by converting a state change, such as a pressurechange applied to the surface, a capacitance change, or a change inquantity of light, into an electrical signal. In FIG. 1, an example inwhich the OLED panel 210 is applied as a display panel is illustrated.The inventive concepts are not limited thereto, and other kinds ofdisplay panels capable of transmitting light may be applied in additionto the OLED panel 210.

The touch panel 220 may be implemented as a resistive type, acapacitance type, a surface acoustic wave type, or an infrared (IR)type. The protection film 230 is disposed on a front surface of thetouch panel 220 and may be formed to have a predetermined thickness toprotect the front surface of the touch panel 220. The protection film230 may prevent/impede reflection of light incident on the touch panel220 from outside of the electronic device 10.

The image sensor 100 may include a plurality of pixels 110 disposed inone-dimensional or two-dimensional array and a printed circuit board(PCB) 120 on which a processor and a drive circuit are disposed fordriving the plurality of pixels 110. Each of the plurality of pixels 110may be formed in a chip shape, and the plurality of chip-shaped pixels110 may be disposed on the PCB 120. Chip-shaped unit pixels may begathered to constitute a pixel array, and the pixel array may bedisposed on the PCB 120.

For example, a complementary metal-oxide semiconductor (CMOS) imagesensor (CIS) may be applied to the image sensor 100. The image sensor100 is configured to convert received light into an electrical signaland may generate a sensed signal when a finger makes contact so as tooutput the sensed signal to the processor. The processor may generate afingerprint image on the basis of the sensed signal received from theimage sensor 100.

The electronic device 10 according to some example embodiments of theinventive concepts may be a device including a communication function.For example, the electronic device 10 may be one among a smartphone, atablet personal computer (PC), a mobile phone, a wearable device (e.g.,a smart watch), an e-book, a notebook computer, a netbook computer, apersonal digital assistant (PDA), a portable multimedia player (PMP), amobile medical device, and a digital camera.

FIG. 2B is a circuit diagram of a unit pixel constituting the pixelarray.

Referring to FIG. 2B, each of the plurality of pixels 110 may include aphotodiode 112 that is an optical sensor and a plurality of transistorsTX, RX, DX, and SX for a readout circuit (RC). The RC may drive thephotodiode 112 and readout an electrical signal generated by thephotodiode 112. The RC may include a transfer transistor TX, a drivingtransistor DX, a selection transistor SX, and a reset transistor RX.

Electrical charges generated at the photodiode 112 may be output to afirst node N1 via the transfer transistor TX. For example, when atransfer control signal TG is at a first level (e.g., high level), thetransfer transistor TX may be turned on. When the transfer transistor TXis turned on, the electrical charges generated at the photodiode 112 maybe output to the first node N1 via the transfer transistor TX.

For example, the driving transistor DX may operate as a source followerbuffer amplifier. The driving transistor DX may amplify a signalcorresponding to the charges charged at the first node N1.

For example, the selection transistor SX may be turned on in response toa selection signal SEL. When the selection transistor SX is turned on,the signal amplified by the driving transistor DX may be transmitted toa column line COL.

For example, the reset transistor RX may be disposed between a VDDterminal and the first node N1. The reset transistor RX may be turned onin response to a reset signal RS. When the reset transistor RX is turnedon, the charges charged at the first node N1 may be reset to the VDDvoltage level. FIG. 2B shows a pixel 110 including a single photodiode112 and four metal oxide semiconductor (MOS) transistors TX, RX, DX, andSX. The inventive concepts are not limited thereto, and each of thepixels 110 may be constituted of a single photodiode 112 and three orless MOS transistors or a single photodiode 112 and five or more MOStransistors.

FIG. 3A shows a pixel of an image sensor according to some exampleembodiments of the inventive concepts and is a diagram illustrating anIR cut-off filter disposed on a light shield grid.

Referring to FIG. 3A, each of the plurality of pixels 110 may includethe photodiode 112, a light shield grid (e.g., a light shieldpattern/layer) 113, a device isolation portion (e.g., device isolationregion or device isolation film) DTI, an IR cut-off filter 114, aplanarization layer 115, and a lens 116.

The photodiode 112 is configured to receive light to generate opticalcharges and may be formed on a silicon substrate. The plurality oftransistors TX, RX, DX, and SX (see FIG. 2B) may be disposed and spacedapart from the photodiode 112 on a layer on which the photodiode 112 isdisposed or may be disposed on a layer different from the layer on whichthe photodiode 112 is disposed. Interconnection lines connecting thephotodiode 112 to the transistors TX, RX, DX, and SX (see FIG. 2B) maybe disposed below the photodiode 112. The photodiode 112 may be disposedon a back side of the silicon substrate, and the interconnection linesmay be disposed on a front side of the silicon substrate that isopposite the back side.

During a manufacturing process of the image sensor 100, the back side ofthe silicon substrate is polished to have a thickness (e.g., 3micrometers (μm)) through which light may transmit such that thephotodiode 112 may be formed on the back side of the silicon substrate.The transistors TX, RX, DX, and SX and the interconnection lines areformed on the front side of the silicon substrate. Then, the lightshield grid 113, the IR cut-off filter 114, the planarization layer 115,and the lens 116 may be disposed above the photodiode 112.

The lens 116 may be disposed at each of the pixels 110. The lens 116 maybe formed in a cylindrical shape or a hemispherical shape so as tocollect incident light at one point. Consequently, light may becollected at the photodiode 112 through the back side of the siliconsubstrate. In a back side illumination (BSI) image sensor 100, theinterconnection lines are disposed below the photodiode 112 (on thefront side of the silicon substrate) such that the incident light is nothindered by the interconnection lines. Thus, the BSI image sensor 100may collect a wide angle of light on the photodiode 112.

The IR cut-off filter 114 is configured to prevent/reduce aphotoelectric effect due to IRs out of a visible ray range and may bedisposed between the planarization layer 115 and the light shield grid113. The IR cut-off filter 114 may be disposed on a front side of eachof the plurality of pixels 110. The light shield grid 113 including anopening 113 a may be disposed below the IR cut-off filter 114 so as toallow light to be incident on the photodiode 112.

The device isolation portion (e.g., device isolation region or deviceisolation film) DTI having a predetermined depth may be disposed betweenthe pixels 110. The device isolation portion DTI is configured to reduceinterference between the pixels 110 and may be disposed around (e.g., tosurround) each of the pixels 110. The device isolation portion DTI maybe formed by forming a trench on the back side of the silicon substrateand then filling the trench with an insulating film. The deviceisolation portion DTI may be formed to have a depth of 1 μm to 5 μm. Thedevice isolation portion DTI may be formed as a deep trench isolationlayer including an insulating material. The device isolation portion DTImay be formed of an insulating material having a refractive index thatis less than that of the silicon substrate, thereby preventing/impedinglight incident on each of the pixels 110 from passing over adjacentpixels 110. The device isolation portion DTI is deeply formed in thesilicon substrate such that light interference between adjacent pixels110 may be prevented/impeded.

Light generated from the OLED panel 210 may be reflected by a finger andbe incident on each of the pixels 110 of the image sensor 100. Light maypass through the lens 116, the planarization layer 115, and the infraredrays/radiation (IR) cut-off filter 114 and be incident on the photodiode112 through the opening 113 a formed by the light shield grid 113. Forexample, the opening 113 a may vertically overlap a portion of thephotodiode 112. Light having a wavelength range corresponding to an IRrange may be blocked by the IR cut-off filter 114.

FIGS. 4A to 4D are diagrams illustrating examples in which a highrefractive index film and a low refractive index film are stacked toform the IR cut-off filter 114.

Referring to FIGS. 3A and 4A, the IR cut-off filter 114 may be formed byalternately stacking different kinds of film to cut-off (i.e., toblock/impede) IRs.

For example, the IR cut-off filter 114 may be constituted of a pluralityof layers formed by a low refractive index film 114L having a firstrefractive index and a high refractive index film 114H having a secondrefractive index that is higher than the first refractive index beingalternately stacked. The IR cut-off filter 114 may be constituted suchthat ten or more low refractive index films 114L and ten or more highrefractive index films 114H are alternately disposed. The IR cut-offfilter 114 may be constituted by stacking ten or more pairs of the lowrefractive index film 114L and the high refractive index film 114H.

The high refractive index film 114H may be disposed at an uppermostlayer of the IR cut-off filter 114. The low refractive index film 114Lmay be disposed on a lowermost layer of the IR cut-off filter 114. Thehigh refractive index film 114H may be disposed below the planarizationlayer 115, and the low refractive index film 114L may be disposed abovethe light shield grid 113. A plurality of low refractive index films114L may have the same refractive index. A plurality of high refractiveindex films 114H may have the same refractive index. The plurality oflow refractive index films 114L may have any one refractive index in therange of 1.2 to 1.8. The plurality of high refractive index films 114Hmay have any one refractive index in the range of 2.0 to 2.8.

The plurality of low refractive index films 114L may be formed with thesame thickness. For example, the plurality of low refractive index films114L may be formed with a thickness of 80 to 160 nm (800 Å to 1,600 Å).The plurality of high refractive index films 114H may be formed with thesame thickness. For example, the plurality of high refractive indexfilms 114H may be formed with a thickness of 80 to 160 nm (800 Å to1,600 Å).

The inventive concepts are not limited thereto, and the plurality of lowrefractive index films 114L may be formed with different thicknesses.For example, the plurality of low refractive index films 114L may havedifferent thicknesses in the range of 80 to 160 nm (800 Å to 1,600 Å).The plurality of high refractive index films 114H may be formed withdifferent thicknesses. For example, the plurality of high refractiveindex films 114H may have different thicknesses within the range of 80to 160 nm (800 Å to 1,600 Å).

Each of the high refractive index film 114H and the low refractive indexfilm 114L of the IR cut-off filter 114 may be formed of an oxide or anitride. Each of the high refractive index film 114H and the lowrefractive index film 114L of the IR cut-off filter 114 may be formed ofa combination of an oxide, a nitride, and a polymer of a transparentmaterial.

For example, each of the high refractive index film 114H and the lowrefractive index film 114L may be formed of one material among titaniumoxide (TiO), tantalum oxide (TaO), hafnium oxide (HfO), lanthanum oxide(LaO), zirconium oxide (ZrO), aluminum oxide (AlO), silicon oxide(SiO₂), silicon nitride (SiN), silicon oxynitride (SiON), and a polymerof a transparent material, or a combination of two or more materialsthereamong. The high refractive index film 114H may be formed of oneoxide, one nitride, or one polymer. The high refractive index film 114Hmay be formed of a combination of two or more materials among an oxide,a nitride, and a polymer. The low refractive index film 114L may beformed of one oxide, one nitride, or one polymer. The low refractiveindex film 114L may be formed of a combination of two or more materialsamong an oxide, a nitride, and a polymer.

Referring to FIGS. 1, 3A, and 4B, the IR cut-off filter 114 may beconstituted of a plurality of layers formed by the low refractive indexfilm 114L having a first refractive index and the high refractive indexfilm 114H having a second refractive index that is higher than the firstrefractive index being alternately stacked.

The low refractive index film 114L may be disposed on the uppermostlayer of the IR cut-off filter 114. The high refractive index film 114Hmay be disposed at the lowermost layer of the IR cut-off filter 114. Thelow refractive index film 114L may be disposed below the planarizationlayer 115, and the high refractive index film 114H may be disposed abovethe light shield grid 113. A plurality of low refractive index films114L may have the same refractive index. A plurality of high refractiveindex films 114H may have the same refractive index. The plurality oflow refractive index films 114L may have any one refractive index in therange of 1.2 to 1.8. The plurality of high refractive index films 114Hmay have any one refractive index in the range of 2.0 to 2.8.

FIGS. 4A and 4B illustrate examples of the IR cut-off filter 114 inwhich ten pairs of the low refractive index film 114L and the highrefractive index film 114H are stacked. The inventive concepts are notlimited thereto, and the IR cut-off filter 114 may be constituted ofnine pairs or fewer of the low refractive index film 114L and the highrefractive index film 114H. The IR cut-off filter 114 may be constitutedof 11 to 20 pairs of the low refractive index film 114L and the highrefractive index film 114H.

Referring to FIGS. 3A and 4C, the IR cut-off filter 114 may beconstituted of a plurality of layers formed by a plurality of lowrefractive index films 114L-1 to 114L-10 and a plurality of highrefractive index films 114H-1 to 114H-10 being alternatively stacked. Atenth high refractive index film 114H-10 may be disposed on/as theuppermost layer of the IR cut-off filter 114. A first low refractiveindex film 114L-1 may be disposed on/as the lowermost layer of the IRcut-off filter 114.

The IR cut-off filter 114 may be constituted such that ten or more lowrefractive index films 114L and ten or more high refractive index films114H are alternately disposed. FIG. 4C shows an example in which the IRcut-off filter 114 may be constituted by stacking ten or more pairs ofthe low refractive index film 114L and the high refractive index film114H.

For example, the first low refractive index film 114L-1 may be disposedon the light shield grid 113, and a first high refractive index film114H-1 may be disposed on the first low refractive index film 114L-1. Asecond low refractive index film 114L-2 having a refractive indexdifferent from that of the first low refractive index film 114L-1 may bedisposed on the first high refractive index film 114H-1. A second highrefractive index film 114H-2 having a refractive index different fromthat of the first high refractive index film 114H-1 may be disposed onthe second low refractive index film 114L-2. A third low refractiveindex film 114L-3 having a refractive index different from that of thesecond low refractive index film 114L-2 may be disposed on the secondhigh refractive index film 114H-2. A third high refractive index film114H-3 having a refractive index different from that of the second highrefractive index film 114H-2 may be disposed on the third low refractiveindex film 114L-3.

Similarly, fourth to tenth low refractive index films and fourth totenth high refractive index films may be alternately stacked. Asdescribed above, ten pairs of the low refractive index film and the highrefractive index film are alternately stacked to constitute the IRcut-off filter 114.

All of the first low refractive index film 114L-1 to the tenth lowrefractive index film 114L-10 may have different refractive indexes.Alternatively, some of the first low refractive index film 114L-1 to thetenth low refractive index film 114L-10 may have the same refractiveindex, whereas the remaining thereof may have different refractiveindexes.

The IR cut-off filter 114 may be constituted by stacking a plurality ofhigh and low refractive index films 114L-1 to 114L-10 and 114H-1 to114H-10 having different refractive indexes.

For example, each of low refractive index films 114L-1 to 114L-10disposed on/as odd-numbered layers among the plurality of refractiveindex films 114L-1 to 114H-10 constituting the IR cut-off filter 114 mayhave a refractive index in the range of 1.2 to 1.8. Each of highrefractive index films 114H-1 to 114H-10 disposed on/as even-numberedlayers among the plurality of refractive index films 114L-1 to 114H-10constituting the IR cut-off filter 114 may have a refractive index inthe range of 2.0 to 2.8.

Alternatively, each of high refractive index films 114H-1 to 114H-10disposed on/as odd-numbered layers among the plurality of refractiveindex films 114L-1 to 114H-10 constituting the IR cut-off filter 114 mayhave a refractive index in the range of 2.0 to 2.8. Each of lowrefractive index films 114L-1 to 114L-10 disposed on/as even-numberedlayers among the plurality of refractive index films 114L-1 to 114H-10constituting the IR cut-off filter 114 may have a refractive index inthe range of 1.2 to 1.8.

The plurality of low refractive index films 114L-1 to 114L-10 may havedifferent refractive indexes in the range of 1.2 to 1.8. For example,the second low refractive index film 114L-2 may have a refractive indexthat is higher than that of the first low refractive index film 114L-1.The third low refractive index film 114L-3 may have a refractive indexthat is higher than that of the second low refractive index film 114L-2.Similarly, the fourth to tenth low refractive index films 114L-4 to114L-10 may have different refractive indexes.

The plurality of high refractive index films 114H-1 to 114H-10 may havedifferent refractive indexes in the range of 2.0 to 2.8. For example,the second high refractive index film 114H-2 may have a refractive indexthat is higher than that of the first high refractive index film 114H-1.The third high refractive index film 114H-3 may have a refractive indexthat is higher than that of the second high refractive index film114H-2. Similarly, the fourth to tenth high refractive index films114H-4 to 114H-10 may have different refractive indexes.

As described above, a pair of the low refractive index film and the highrefractive index film may be formed, and ten pairs or more of the lowrefractive index films and the high refractive index films may bealternately disposed to constitute the IR cut-off filter 114.

For example, the refractive indexes of the first to tenth highrefractive index films 114H-1 to 114H-10 constituting the IR cut-offfilter 114 may become lower in a direction from a side at which light isincident toward the photodiode 112.

Moreover, the refractive indexes of the first to tenth low refractiveindex films 114L-1 to 114L-10 constituting the IR cut-off filter 114 maybecome lower in the direction from the side at which the light isincident toward the photodiode 112.

In some embodiments, the refractive indexes of the first to tenth highrefractive index films 114H-1 to 114H-10 constituting the IR cut-offfilter 114 may become higher in the direction from the side at which thelight is incident toward the photodiode 112.

Moreover, the refractive indexes of the first to tenth low refractiveindex films 114L-1 to 114L-10 constituting the IR cut-off filter 114 maybecome higher in the direction from the side at which the light isincident toward the photodiode 112.

The first to tenth low refractive index films 114L-1 to 114L-10 may beformed with the same thickness. For example, the first to tenth lowrefractive index films 114L-1 to 114L-10 may be formed with a thicknessof 80 nm to 160 nm (800 Å to 1,600 Å).

The first to tenth high refractive index films 114H-1 to 114H-10 may beformed with the same thickness. For example, the first to tenth highrefractive index films 114H-1 to 114H-10 may be formed with a thicknessof 80 nm to 160 nm (800 Å to 1,600 Å).

The inventive concepts are not limited thereto, the first to the tenthlow refractive index films 114L-1 to 114L-10 may be formed withdifferent thicknesses. For example, the first to tenth low refractiveindex films 114L-1 to 114L-10 may have different thicknesses in therange of 80 nm to 160 nm (800 Å to 1,600 Å).

The first to tenth high refractive index films 114H-1 to 114H-10 may beformed with different thicknesses. For example, the first to tenth highrefractive index films 114H-1 to 114H-10 may have different thicknessesin the range of 80 nm to 160 nm (800 Å to 1,600 Å).

Referring to FIGS. 3A and 4D, the IR cut-off filter 114 may beconstituted of a plurality of layers formed by a plurality of lowrefractive index films 114L-1 to 114L-10 and a plurality of highrefractive index films 114H-1 to 114H-10 being alternatively stacked. Atenth low refractive index film 114L-10 may be disposed on/as theuppermost layer of the IR cut-off filter 114. A first high refractiveindex film 114H-1 may be disposed on/as the lowermost layer of the IRcut-off filter 114.

The first high refractive index film 114H-1 may be disposed on the lightshield grid 113, and a first low refractive index film 114L-1 may bedisposed on the first high refractive index film 114H-1. A second highrefractive index film 114H-2 having a refractive index different fromthat of the first high refractive index film 114H-1 may be disposed onthe first low refractive index film 114L-1. A second low refractiveindex film 114L-2 having a refractive index different from that of thefirst low refractive index film 114L-1 may be disposed on the secondhigh refractive index film 114H-2. A third high refractive index film114H-3 having a refractive index different from that of the second highrefractive index film 114H-2 may be disposed on the second lowrefractive index film 114L-2. A third low refractive index film 114L-3having a refractive index different from that of the second lowrefractive index film 114L-2 may be disposed on the third highrefractive index film 114H-3. Similarly, the fourth to tenth lowrefractive index films 114L-4 to 114L-10 may have different refractiveindexes. As described above, a pair of the low refractive index film andthe high refractive index film may be formed, and ten or more pairs ofthe low refractive index films and the high refractive index films maybe alternately disposed to constitute the IR cut-off filter 114.

For example, the plurality of low refractive index films 114L-1 to114L-10 may have different refractive indexes in the range of 1.2 to1.8. The plurality of high refractive index films 114H-1 to 114H-10 mayhave different refractive indexes in the range of 2.0 to 2.8.

For example, the refractive indexes of the first to tenth highrefractive index films 114H-1 to 114H-10 constituting the IR cut-offfilter 114 may become lower in a direction from a side at which light isincident toward the photodiode 112.

Moreover, the refractive indexes of the first to tenth low refractiveindex films 114L-1 to 114L-10 constituting the IR cut-off filter 114 maybecome lower in the direction from the side at which the light isincident toward the photodiode 112.

In some embodiments, the refractive indexes of the first to tenth highrefractive index films 114H-1 to 114H-10 constituting the IR cut-offfilter 114 may become higher in the direction from the side at which thelight is incident toward the photodiode 112.

Moreover, the refractive indexes of the first to tenth low refractiveindex films 114L-1 to 114L-10 constituting the IR cut-off filter 114 maybecome higher in the direction from the side at which the light isincident toward the photodiode 112.

FIGS. 4C and 4D illustrate examples of the IR cut-off filter 114 inwhich ten pairs of the low refractive index films and the highrefractive index films are stacked. The inventive concepts are notlimited thereto, and the IR cut-off filter 114 may be constituted ofnine pairs or fewer of the low refractive index films and the highrefractive index films. The IR cut-off filter 114 may be constituted of11 to 20 pairs of the low refractive index films and the high refractiveindex films.

FIGS. 5A and 5B are diagrams illustrating a light shield grid of theimage sensor of the inventive concept.

As shown in FIG. 5A, the light shield grid 113 may be formed to have acircular opening 113 a.

As shown in FIG. 5B, the light shield grid 113 may be formed to have aquadrangular opening 113 a.

The light shield grid 113 may be formed of a metal material such astungsten (W). The image sensor 100 of the inventive concepts isconfigured to generate a fingerprint image of a finger, and the opening113 a of the light shield grid 113 may be formed to be very small. Lightmay be guided to be incident on the photodiode 112 by the opening 113 aof the light shield grid 113. The opening 113 a of the light shield grid113 may be disposed to correspond to a central portion of the pixel 110.The opening 113 a of the light shield grid 113 may be disposed tocorrespond to a central portion of the photodiode 112. Light may beincident on the photodiode 112 of each of the pixels 110 without passingover another pixel 110 by the opening 113 a disposed to correspond toeach of the pixels 110. The opening 113 a may include (e.g., may befilled with) a transparent layer formed of a transparent material.

For example, the opening 113 a of the light shield grid 113 may beformed to correspond to an area of 1 to 15% of each of the pixels 110.An area of 1 to 15% of the pixel 110 is opened by the opening 113 a.Light may be incident on the photodiode 112 through the opening 113 a,which is formed to be smaller than the area of the pixel 110. Since theopening 113 a of the light shield grid 113 is formed to be very small,light may be accurately incident on the photodiode 112 without passingover adjacent pixels 110.

In order to suppress a dark current which may occur in the photodiode112, a voltage of 0 V to −2 V may be applied to the light shield grid113.

The planarization layer 115 may be formed to cover the IR cut-off filter114. An upper surface on which the lens 116 is disposed may beplanarized by the planarization layer 115. For example, theplanarization layer 115 may be formed of a single film selected from thegroup consisting of an oxide film, a nitride film, and an oxynitridefilm. Alternatively, the planarization layer 115 may be formed of two ormore stacked films selected from the group consisting of an oxide film,a nitride film, and an oxynitride film.

FIG. 3B is a diagram illustrating a dark current suppression layerdisposed in the pixel 110 shown in FIG. 3A.

As shown in FIG. 3B, the device isolation portion (e.g., deviceisolation region or device isolation film) DTI having a predetermineddepth may be disposed between the pixels 110. A dark current suppressionlayer 111 may be disposed above the device isolation portion DTI and thephotodiode 112. The light shield grid 113 may be disposed on the darkcurrent suppression layer 111. The IR cut-off filter 114 may be disposedon the light shield grid 113.

For example, the device isolation portion DTI may be formed in the backside of the silicon substrate, and the dark current suppression layer111 may be disposed above the device isolation portion DTI and thephotodiode 112.

A voltage of 0 V to −2 V is applied to the light shield grid 113 and thedark current suppression layer 111 is disposed such that generation of adark current from the photodiode 112 may be prevented/impeded.

The dark current suppression layer 111 may be formed by stacking aplurality of layers, each of which have a fixed negative charge. Each ofthe plurality of layers constituting the dark current suppression layer111 may be formed of one material or a combination of two or morematerials selected from the group consisting of AlO, TaO, HfO, ZrO, andLaO.

For example, the dark current suppression layer 111 may be constitutedby stacking two layers. The dark current suppression layer 111 in whichan AlO layer and a TaO layer are stacked may be disposed above thephotodiode 112. The dark current suppression layer 111 may be disposedon the front (or back) side of the silicon substrate to overlap thephotodiode 112. The AlO layer may be disposed at a lower portion of thedark current suppression layer 111, and the TaO layer may be disposed onthe AlO layer. The inventive concepts are not limited thereto. The TaOlayer may be disposed in the lower portion of the dark currentsuppression layer 111, and the AlO layer may be disposed on the TaOlayer. The AlO layer and the TaO layer may be disposed with the samethickness in the dark current suppression layer 111. The inventiveconcepts are not limited thereto, and the AlO layer and the TaO layermay be disposed with different thicknesses in the dark currentsuppression layer 111.

As another example, the dark current suppression layer 111 may beconstituted by stacking two layers. The dark current suppression layer111 in which the AlO layer and a HfO layer are stacked may be disposedabove the photodiode 112. The dark current suppression layer 111 may bedisposed on the front (or back) side of the silicon substrate to overlapthe photodiode 112. The AlO layer may be disposed in the lower portionof the dark current suppression layer 111, and the HfO layer may bedisposed on the AlO layer. The inventive concepts are not limitedthereto. The HfO layer may be disposed in the lower portion of the darkcurrent suppression layer 111, and the AlO layer may be disposed on theHfO layer. The AlO layer and the HfO layer may be disposed with the samethickness in the dark current suppression layer 111. The inventiveconcepts are not limited thereto. The AlO layer and the HfO layer may bedisposed with different thicknesses in the dark current suppressionlayer 111.

As a further example, the dark current suppression layer 111 may beconstituted by stacking two layers. The dark current suppression layer111 in which the HfO layer and a ZrO layer are stacked may be disposedto overlap the photodiode 112. Alternatively, the dark currentsuppression layer 111 in which the ZrO layer and a LaO layer are stackedmay be disposed above the photodiode 112. The ZrO layer may be disposedin the lower portion of the dark current suppression layer 111, and theLaO layer may be disposed on the ZrO layer. The inventive concepts arenot limited thereto, and the LaO layer may be disposed in the lowerportion of the dark current suppression layer 111, and a ZrO layer maybe disposed on the LaO layer. The ZrO layer and the LaO layer may bedisposed with the same thickness in the dark current suppression layer111. The inventive concepts are not limited thereto, and the ZrO layerand the LaO layer may be disposed with different thicknesses in the darkcurrent suppression layer 111.

In addition to the above-described combinations of layers, a first layerof the dark current suppression layer 111 may be formed of one materialamong AlO, TaO, HfO, ZrO, and LaO. A second layer of the dark currentsuppression layer 111 may be formed of another material different fromthe material of the first layer. The dark current suppression layer 111may be formed by stacking the second layer on the first layer.

In some embodiments, the dark current suppression layer 111 may beconstituted by stacking three layers. The dark current suppression layer111 in which the AlO layer, the TaO layer, and the HfO layer are stackedmay be disposed above the photodiode 112. The AlO layer may be disposedas a first layer of the dark current suppression layer 111. The TaOlayer may be disposed as a second layer of the dark current suppressionlayer 111. The HfO layer may be disposed as a third layer of the darkcurrent suppression layer 111. The first layer may be disposed at alowermost position of the dark current suppression layer 111, the secondlayer may be disposed on the first layer, and the third layer may bedisposed on the second layer. The inventive concepts are not limitedthereto, and the positions of the AlO layer, the TaO layer, and the HfOlayer in the dark current suppression layer 111 may be changed with oneanother. The AlO layer, the TaO layer, and the HfO layer may be disposedwith the same thickness in the dark current suppression layer 111. Theinventive concepts are not limited thereto, and the AlO layer, the TaOlayer, and the HfO layer may be disposed with different thicknesses inthe dark current suppression layer 111.

In some embodiments, the dark current suppression layer 111 may beconstituted by stacking three layers. The dark current suppression layer111 in which the TaO layer, the HfO layer, and the ZrO layer are stackedmay be disposed above the photodiode 112. The TaO layer may be disposedas a first layer of the dark current suppression layer 111. The HfOlayer may be disposed as a second layer of the dark current suppressionlayer 111. The ZrO layer may be disposed as a third layer of the darkcurrent suppression layer 111. The first layer may be disposed at alowermost position of the dark current suppression layer 111, the secondlayer may be disposed on the first layer, and the third layer may bedisposed on the second layer. The inventive concepts are not limitedthereto, and the positions of the TaO layer, the HfO layer, and the ZrOlayer in the dark current suppression layer 111 may be changed with oneanother. The TaO layer, the HfO layer, and the ZrO layer may be disposedwith the same thickness in the dark current suppression layer 111. Theinventive concepts are not limited thereto, and the TaO layer, the HfOlayer, and the ZrO layer may be disposed with different thicknesses inthe dark current suppression layer 111.

In some embodiments, the dark current suppression layer 111 may beconstituted by stacking three layers. The dark current suppression layer111 in which the HfO layer, the ZrO layer, and the LaO layer are stackedmay be disposed above the photodiode 112. The HfO layer may be disposedas a first layer of the dark current suppression layer 111. The ZrOlayer may be disposed as a second layer of the dark current suppressionlayer 111. The LaO layer may be disposed as a third layer of the darkcurrent suppression layer 111. The first layer may be disposed at alowermost position of the dark current suppression layer 111, the secondlayer may be disposed on the first layer, and the third layer may bedisposed on the second layer. The inventive concepts are not limitedthereto, and the positions of the HfO layer, the ZrO layer, and the LaOlayer in the dark current suppression layer 111 may be changed with oneanother. The HfO layer, the ZrO layer, and the LaO layer may be disposedwith the same thickness in the dark current suppression layer 111. Theinventive concepts are not limited thereto, and the HfO layer, the ZrOlayer, and the LaO layer may be disposed with different thicknesses inthe dark current suppression layer 111.

In addition to the above-described combinations of layers, the firstlayer of the dark current suppression layer 111 may be formed of onematerial among AlO, TaO, HfO, ZrO, and LaO. The second layer of the darkcurrent suppression layer 111 may be formed of another materialdifferent from the material of the first layer. The third layer of thedark current suppression layer 111 may be formed of another materialdifferent from the materials of the first layer and the second layer.

In some embodiments, the dark current suppression layer 111 may beconstituted by stacking four layers. The dark current suppression layer111 in which the AlO layer, the TaO layer, the HfO layer, and the ZrOare stacked may be disposed above the photodiode 112. The AlO layer maybe disposed as a first layer of the dark current suppression layer 111.The TaO layer may be disposed as a second layer of the dark currentsuppression layer 111. The HfO layer may be disposed as a third layer ofthe dark current suppression layer 111. The ZrO layer may be disposed asa fourth layer of the dark current suppression layer 111. The firstlayer may be disposed at a lowermost position of the dark currentsuppression layer 111, the second layer may be disposed on the firstlayer, the third layer may be disposed on the second layer, and thefourth layer may be disposed on the third layer. The inventive conceptsare not limited thereto, and the positions of the AlO layer, the TaOlayer, the HfO layer, and the ZrO layer in the dark current suppressionlayer 111 may be changed with one another. The AlO layer, the TaO layer,the HfO layer, and the ZrO layer may be disposed with the same thicknessin the dark current suppression layer 111. The inventive concepts arenot limited thereto, and the AlO layer, the TaO layer, the HfO layer,and the ZrO layer may be disposed with different thicknesses in the darkcurrent suppression layer 111.

In some embodiments, the dark current suppression layer 111 may beconstituted by stacking four layers. The dark current suppression layer111 in which the TaO layer, the HfO layer, the ZrO layer, and the LaOlayer are stacked may be disposed above the photodiode 112. The TaOlayer may be disposed as a first layer of the dark current suppressionlayer 111. The HfO layer may be disposed as a second layer of the darkcurrent suppression layer 111. The ZrO layer may be disposed as a thirdlayer of the dark current suppression layer 111. The LaO layer may bedisposed as a fourth layer of the dark current suppression layer 111.The first layer may be disposed at a lowermost position of the darkcurrent suppression layer 111, the second layer may be disposed on thefirst layer, the third layer may be disposed on the second layer, andthe fourth layer may be disposed on the third layer. The inventiveconcepts are not limited thereto, and the positions of the TaO layer,the HfO layer, the ZrO layer, and the LaO layer in the dark currentsuppression layer 111 may be changed with one another. The TaO layer,the HfO layer, the ZrO layer, and the LaO layer may be disposed with thesame thickness in the dark current suppression layer 111. The inventiveconcepts are not limited thereto, and the TaO layer, the HfO layer, theZrO layer, and the LaO layer may be disposed with different thicknessesin the dark current suppression layer 111.

In some embodiments, the dark current suppression layer 111 may beconstituted by stacking four layers. The dark current suppression layer111 in which the AlO layer, the TaO layer, the HfO layer, and the LaOare stacked may be disposed above the photodiode 112. The AlO layer maybe disposed as a first layer of the dark current suppression layer 111.The TaO layer may be disposed as a second layer of the dark currentsuppression layer 111. The HfO layer may be disposed as a third layer ofthe dark current suppression layer 111. The LaO layer may be disposed asa fourth layer of the dark current suppression layer 111. The firstlayer may be disposed at a lowermost position of the dark currentsuppression layer 111, the second layer may be disposed on the firstlayer, the third layer may be disposed on the second layer, and thefourth layer may be disposed on the third layer. The inventive conceptsare not limited thereto, and the positions of the AlO layer, the TaOlayer, the HfO layer, and the LaO layer in the dark current suppressionlayer 111 may be changed with one another. The AlO layer, the TaO layer,the HfO layer, and the LaO layer may be disposed with the same thicknessin the dark current suppression layer 111. The inventive concepts arenot limited thereto, and the AlO layer, the TaO layer, the HfO layer,and the LaO layer may be disposed with different thicknesses in the darkcurrent suppression layer 111.

In addition to the above-described combinations of layers, the firstlayer of the dark current suppression layer 111 may be formed of onematerial among AlO, TaO, HfO, ZrO, and LaO. The second layer of the darkcurrent suppression layer 111 may be formed of another materialdifferent from the material of the first layer. The third layer of thedark current suppression layer 111 may be formed of another materialdifferent from the materials of the first layer and the second layer.The fourth layer of the dark current suppression layer 111 may be formedof another material different from the materials of the first layer, thesecond layer, and the third layer. The first to fourth layers may besequentially stacked to form the dark current suppression layer 111.

FIG. 3C is a diagram illustrating the device isolation portion and thedark current suppression layer in detail.

Referring to FIG. 3C, the dark current suppression layer 111 may beintegrally formed with the device isolation portion (e.g., deviceisolation region or device isolation film) DTI. The dark currentsuppression layer 111 may be formed on the front (or back) side of thesilicon substrate. For example, after a trench is formed, the darkcurrent suppression layer 111 and the device isolation portion DTI, eachof which include a plurality of layers, may be formed in the front (orback) side of the silicon substrate and the trench. Each of the darkcurrent suppression layer 111 and the device isolation portion DTI maybe formed in/as a structure in which a plurality of layers are stacked.When each of the dark current suppression layer 111 and the deviceisolation portion DTI is formed with four layers, a first layer L1thereof may be formed of one material among AlO, TaO, HfO, ZrO, and LaO.A second layer L2 may be formed of a material different from thematerial of the first layer L1. A third layer L3 may be formed of amaterial different from the materials of the first layer L1 and thesecond layer L2. A fourth layer L4 may be formed of a material differentfrom the materials of the first to third layers L1, L2, and L3. Theinventive concepts are not limited thereto, and each of the dark currentsuppression layer 111 and the device isolation portion DTI may also beformed with two to three layers or five or more layers. When the darkcurrent suppression layer 111 and the device isolation portion DTI areintegrally formed, each of the dark current suppression layer 111 andthe device isolation portion DTI may be formed by stacking a pluralityof layers, each of which have a fixed negative charge.

FIG. 6A is a diagram illustrating an IR cut-off filter disposed belowthe light shield grid according to some example embodiments of theinventive concepts. FIG. 6B is a diagram illustrating the dark currentsuppression layer disposed in the pixel 110 shown in FIG. 6A. Indescribing the pixel 110 shown in FIGS. 6A and 6B, a description of astructure that is the same as that of the pixel 110 shown in FIGS. 3A to3C will be omitted.

Referring to FIGS. 1 and 6A, each of the plurality of pixels 110 mayinclude the photodiode 112, the light shield grid 113, the deviceisolation portion (e.g., device isolation region or device isolationfilm) DTI, the IR cut-off filter 114, the planarization layer 115, andthe lens 116.

During a manufacturing process of the image sensor 100, the back side ofthe silicon substrate is polished to have a thickness (e.g., 3 μm)through which light may transmit such that the photodiode 112 may beformed on the back side of the silicon substrate. The transistors TX,RX, DX, and SX and the lines are formed on the front side of the siliconsubstrate. Then, the IR cut-off filter 114, the light shield grid 113,the planarization layer 115, and the lens 116 may be disposed above thephotodiode 112.

In the BSI image sensor 100, the lines are disposed below the photodiode112 (on the front side of the silicon substrate) such that the incidentlight is not hindered by the lines. Thus, the image sensor 100 maycollect a wide angle of light on the photodiode 112.

The device isolation portion DTI having a predetermined depth may bedisposed between the pixels 110. The device isolation portion DTI isconfigured to reduce interference between the pixels 110 and may bedisposed to surround each of the pixels 110. The device isolationportion DTI may be formed by forming a trench on the back side of thesilicon substrate and then filling the trench with an insulating film.The device isolation portion DTI may be formed to have a depth of 1 μmto 5 μm. The device isolation portion DTI may be formed as a deep trenchisolation layer including an insulating material. The device isolationportion DTI may be formed of an insulating material having a refractiveindex that is less than that of the silicon substrate, therebypreventing/impeding light incident on each of the pixels 110 frompassing over adjacent pixels 110. The device isolation portion DTI isdeeply formed in the silicon substrate such that light interferencebetween adjacent pixels 110 may be prevented/impeded.

The IR cut-off filter 114 is configured to prevent/reduce aphotoelectric effect due to IRs out of a visible ray range and may bedisposed between the photodiode 112 and the light shield grid 113. Thelight shield grid 113 including an opening 113 a may be disposed on theIR cut-off filter 114 so as to allow light to be incident on thephotodiode 112. A transparent layer formed of a transparent material maybe disposed in the opening 113 a.

Light generated from the OLED panel 210 may be reflected by a finger andbe incident on each of the pixels 110 of the image sensor 100. The lightpasses through the lens 116 and the planarization layer 115. Then, thelight is incident on the IR cut-off filter 114 via the opening 113 aformed by the light shield grid 113. The light passing through the IRcut-off filter 114 may be incident on the photodiode 112. Light having awavelength range corresponding to an IR range may be cut-off by the IRcut-off filter 114.

The light shield grid 113 may be formed of a metal material such as W.The image sensor 100 of the inventive concepts is configured to generatea fingerprint image of a finger, and the opening 113 a of the lightshield grid 113 may be formed to be very small (see FIGS. 5A and 5B).

For example, the opening 113 a of the light shield grid 113 may beformed to correspond to an area of 1 to 15% of each of the pixels 110.An area of 1 to 15% of the pixel 110 is opened by the opening 113 a.Light may be incident on the photodiode 112 through the opening 113 a,which is formed to be smaller than the area of the pixel 110. Since theopening 113 a of the light shield grid 113 is formed to be very small,light may be accurately incident on the photodiode 112 without passingover adjacent pixels 110.

In order to suppress a dark current which may occur in the photodiode112, a voltage of 0 V to −2 V may be applied to the light shield grid113.

Referring to FIG. 6B, the device isolation portion DTI having apredetermined depth may be disposed between the pixels 110. The darkcurrent suppression layer 111 may be disposed above the device isolationportion DTI and the photodiode 112. The IR cut-off filter 114 may bedisposed on the dark current suppression layer 111. The light shieldgrid 113 may be disposed on the IR cut-off filter 114.

For example, the device isolation portion DTI may be formed in the backside of the silicon substrate, and the dark current suppression layer111 may be disposed above the device isolation portion DTI and thephotodiode 112.

The dark current suppression layer 111 may be formed on the front (orback) side of the silicon substrate. A voltage of 0 V to −2 V is appliedto the light shield grid 113, and the dark current suppression layer 111is disposed such that generation of a dark current from the photodiode112 may be prevented/impeded.

The dark current suppression layer 111 may be formed by stacking aplurality of layers, each of which have a fixed negative charge. Each ofthe plurality of layers constituting the dark current suppression layer111 may be formed of one material or a combination of two or morematerials selected from the group consisting of AlO, TaO, HfO, ZrO, andLaO.

For example, as shown in FIG. 6B, the dark current suppression layer 111and the device isolation portion DTI may be integrated and formed of aplurality of layers. When the dark current suppression layer 111 and thedevice isolation portion DTI are integrally formed, each of the darkcurrent suppression layer 111 and the device isolation portion DTI maybe formed by stacking a plurality of layers, each of which have a fixednegative charge.

FIG. 7A is a diagram illustrating the IR cut-off filter disposed on thelight shield grid and a light cut-off filter layer disposed on the IRcut-off filter according to some example embodiments of the inventiveconcepts. FIG. 7B is a diagram illustrating the dark current suppressionlayer disposed in the pixel 110 shown in FIG. 7A. In describing thepixel 110 shown in FIGS. 7A and 7B, a description of a structure that isthe same as that of the pixel 110 shown in FIGS. 3A to 3C will beomitted.

Referring to FIGS. 1 and 7A, each of the plurality of pixels 110 mayinclude the photodiode 112, the light shield grid 113, the deviceisolation portion (e.g., device isolation region or device isolationfilm) DTI, the IR cut-off filter 114, a light cut-off filter layer 117,the planarization layer 115, and the lens 116.

During a manufacturing process of the image sensor 100, the back side ofthe silicon substrate is polished to have a thickness (e.g., 3 μm)through which light may transmit such that the photodiode 112 may beformed on the back side of the silicon substrate. The transistors TX,RX, DX, and SX and the lines are formed on the front side of the siliconsubstrate. Then, the light shield grid 113, the IR cut-off filter 114,the light cut-off filter layer 117, the planarization layer 115, and thelens 116 may be disposed above the photodiode 112.

The device isolation portion DTI having a predetermined depth may bedisposed between the pixels 110. The device isolation portion DTI isconfigured to reduce interference between the pixels 110 and may bedisposed to surround each of the pixels 110. The device isolationportion DTI may be formed by forming a trench on the back side of thesilicon substrate and then filling the trench with an insulating film.The device isolation portion DTI may be formed to have a depth of 1 μmto 5 μm. The device isolation portion DTI may be formed as a deep trenchisolation layer including an insulating material. The device isolationportion DTI may be formed of an insulating material having a refractiveindex that is less than that of the silicon substrate, therebypreventing/impeding light incident on each of the pixels 110 frompassing over adjacent pixels 110. The device isolation portion DTI isdeeply formed in the silicon substrate such that light interferencebetween adjacent pixels 110 may be prevented/impeded.

The light shield grid 113 may be disposed above the photodiode 112. TheIR cut-off filter 114 may be disposed on the light shield grid 113. Thelight cut-off filter layer 117 may be disposed on the IR cut-off filter114. The planarization layer 115 may be disposed on the light cut-offfilter layer 117. The lens 116 may be disposed on the planarizationlayer 115.

The light shield grid 113 may be formed of a metal material such as W.The image sensor 100 of the inventive concepts is configured to generatea fingerprint image of a finger, and the opening 113 a of the lightshield grid 113 may be formed to be very small (see FIGS. 5A and 5B).

For example, the opening 113 a of the light shield grid 113 may beformed to correspond to an area of 1 to 15% of each of the pixels 110.An area of 1 to 15% of the pixel 110 is opened by the opening 113 a.Light may be incident on the photodiode 112 through the opening 113 a,which is formed to be smaller than the area of the pixel 110. Since theopening 113 a of the light shield grid 113 is formed to be very small,light may be accurately incident on the photodiode 112 without passingover adjacent pixels 110.

In order to suppress a dark current which may occur in the photodiode112, a voltage of 0 V to −2 V may be applied to the light shield grid113.

The IR cut-off filter 114 is configured to prevent/reduce aphotoelectric effect due to IRs out of a visible ray range and may bedisposed above the photodiode 112 and the light shield grid 113.

The light shield grid 113 may be formed of a metal material such as W.Light incident on the pixel 110 may be reflected from an upper surfaceof the light shield grid 113. In this case, the light reflected from thesupper surface of the light shield grid 113 is visible at the outside ofthe pixel 110. Owing to the light reflected from the upper surface ofthe light shield grid 113, quality of an image displayed on the OLEDpanel 210 may be degraded. According to the inventive concepts, in orderto prevent/impede reflection of light from the upper surface of thelight shield grid 113, the light cut-off filter layer 117 may bedisposed above the light shield grid 113.

For example, in order to prevent/impede reflection of light from theupper surface of the light shield grid 113, the light cut-off filterlayer 117 may be disposed in a form in which a red color filter, a greencolor filter, and a blue color filter are stacked.

For example, the light cut-off filter layer 117 may be formed in astructure in which two or more color filters selected from the groupconsisting of a red color filter, a green color filter, a blue colorfilter, a cyan color filter, a magenta color filter, and a yellow colorfilter are stacked.

The color filters constituting the light cut-off filter layer 117 may beformed of an organic material. The organic material used for the colorfilter may be one material or a combination of two or more materialsselected from the group consisting of polyacetylene, poly(p-phenylene),polythiophene, poly(3,4-ethylenedioxy thiophene) (PEDOT), polypyrrole,poly(p-phenylene sulfide), poly(p-phenylene vinylene), and polyaniline.

Light generated from the OLED panel 210 may be reflected by a finger andbe incident on each of the pixels 110 of the image sensor 100. The lightpasses through the lens 116 and the planarization layer 115. The lightmay pass through the IR cut-off filter 114 and be incident on thephotodiode 112 via the opening 113 a formed by the light shield grid113. Light having a wavelength range corresponding to an IR range may becut-off by the IR cut-off filter 114.

Referring to FIG. 7B, the device isolation portion DTI having apredetermined depth may be disposed between the pixels 110. The darkcurrent suppression layer 111 may be disposed above the device isolationportion DTI and the photodiode 112. The light shield grid 113 may bedisposed on the dark current suppression layer 111. The IR cut-offfilter 114 may be disposed on the light shield grid 113. The lightcut-off filter layer 117 may be disposed on the IR cut-off filter 114.The planarization layer 115 may be disposed on the light cut-off filterlayer 117. The lens 116 may be disposed on the planarization layer 115.

For example, the device isolation portion DTI may be formed in the backside of the silicon substrate, and the dark current suppression layer111 may be disposed above the device isolation portion DTI and thephotodiode 112. The dark current suppression layer 111 may be integrallyformed with the device isolation portion DTI. The dark currentsuppression layer 111 may be formed on the front (or back) side of thesilicon substrate. A voltage of 0 V to −2 V is applied to the lightshield grid 113, and the dark current suppression layer 111 is disposedsuch that generation of a dark current from the photodiode 112 may beprevented/impeded.

The dark current suppression layer 111 may be formed by stacking aplurality of layers, each of which have a fixed negative charge. Each ofthe plurality of layers constituting the dark current suppression layer111 may be formed of one material or a combination of two or morematerials selected from the group consisting of AlO, TaO, HfO, ZrO, andLaO.

For example, as shown in FIG. 3C, the dark current suppression layer 111and the device isolation portion DTI may be integrated and formed of aplurality of layers. When the dark current suppression layer 111 and thedevice isolation portion DTI are integrally formed, each of the darkcurrent suppression layer 111 and the device isolation portion DTI maybe formed by stacking a plurality of layers, each of which have a fixednegative charge. As shown in FIGS. 4A and 4B, the IR cut-off filter 114may be constituted of a plurality of layers formed by the plurality oflow refractive index films 114L having the same refractive index and theplurality of high refractive index films 114H having the same refractiveindex being alternately stacked.

As shown in FIGS. 4C and 4D, the IR cut-off filter 114 may beconstituted of a plurality of layers formed by the plurality of highrefractive index films 114H-1 to 114H-10 having different refractiveindexes and the plurality of low refractive index films 114L-1 to114L-10 having different refractive indexes being alternately stacked.

In order to prevent/impede reflection of light from the upper surface ofthe light shield grid 113, the light cut-off filter layer 117 may bedisposed in a form in which a red color filter, a green color filter,and a blue color filter are stacked.

The light cut-off filter layer 117 may be formed in a structure in whichtwo or more color filters selected from the group consisting of a redcolor filter, a green color filter, a blue color filter, a cyan colorfilter, a magenta color filter, and a yellow color filter are stacked.

FIG. 8A is a diagram illustrating the light cut-off filter layerdisposed on the light shield grid and the IR cut-off filter is disposedbelow the light shield grid according to some example embodiments of theinventive concepts. FIG. 8B is a diagram illustrating and the darkcurrent suppression layer disposed in the pixel 110 shown in FIG. 8A. Indescribing the pixel 110 shown in FIGS. 8A and 8B, a description of astructure that is the same as that of the pixel 110 shown in FIGS. 3A to3C will be omitted.

Referring to FIGS. 1 and 8A, each of the plurality of pixels 110 mayinclude the photodiode 112, the light shield grid 113, the deviceisolation portion (e.g., device isolation region or device isolationfilm) DTI, the IR cut-off filter 114, the light cut-off filter layer117, the planarization layer 115, and the lens 116.

The photodiode 112 may be formed on the back side of the siliconsubstrate. The transistors TX, RX, DX, and SX and the lines are formedon the front side of the silicon substrate. Then, the IR cut-off filter114, the light shield grid 113, the light cut-off filter layer 117, theplanarization layer 115, and the lens 116 may be disposed above thephotodiode 112.

The device isolation portion DTI having a predetermined depth may bedisposed between the pixels 110. The device isolation portion DTI isconfigured to reduce interference between the pixels 110 and may bedisposed to surround each of the pixels 110. The device isolationportion DTI may be formed by forming a trench on the back side of thesilicon substrate and then filling the trench with an insulating film.The device isolation portion DTI may be formed to have a depth of 1 μmto 5 μm. The device isolation portion DTI may be formed as a deep trenchisolation layer including an insulating material. The device isolationportion DTI may be formed of an insulating material having a refractiveindex that is less than that of the silicon substrate, therebypreventing/impeding light incident on each of the pixels 110 frompassing over adjacent pixels 110. The device isolation portion DTI isdeeply formed in the silicon substrate such that light interferencebetween adjacent pixels 110 may be prevented/impeded.

The IR cut-off filter 114 may be disposed above the photodiode 112. Thelight shield grid 113 may be disposed on the IR cut-off filter 114. Thelight cut-off filter layer 117 may be disposed on the light shield grid113. The planarization layer 115 may be disposed on the light cut-offfilter layer 117. The lens 116 may be disposed on the planarizationlayer 115.

The light shield grid 113 may be formed of a metal material such as W.The image sensor 100 of the inventive concepts is configured to generatea fingerprint image of a finger, and the opening 113 a of the lightshield grid 113 may be formed to be very small (see FIGS. 5A and 5B).

For example, the opening 113 a of the light shield grid 113 may beformed to correspond to an area of 1 to 15% of each of the pixels 110.An area of 1 to 15% of the pixel 110 is opened by the opening 113 a.Light may be incident on the photodiode 112 through the opening 113 a,which is formed to be smaller than the area of the pixel 110. Since theopening 113 a of the light shield grid 113 is formed to be very small,light may be accurately incident on the photodiode 112 without passingover adjacent pixels 110.

In order to suppress a dark current which may occur in the photodiode112, a voltage of 0 V to −2 V may be applied to the light shield grid113.

The IR cut-off filter 114 is configured to prevent/reduce aphotoelectric effect due to IRs out of a visible ray range and may bedisposed above the photodiode 112 and the light shield grid 113.

The light shield grid 113 may be formed of a metal material such as W.Light incident on the pixel 110 may be reflected from an upper surfaceof the light shield grid 113. In this case, the light reflected from thesupper surface of the light shield grid 113 is visible at the outside ofthe pixel 110. Owing to the light reflected from the upper surface ofthe light shield grid 113, quality of an image displayed on the OLEDpanel 210 may be degraded. According to the inventive concepts, in orderto prevent/impede reflection of light from the upper surface of thelight shield grid 113, the light cut-off filter layer 117 may bedisposed on above the light shield grid 113.

For example, in order to prevent/impede reflection of light from theupper surface of the light shield grid 113, the light cut-off filterlayer 117 may be disposed in a form in which a red color filter, a greencolor filter, and a blue color filter are stacked.

For example, the light cut-off filter layer 117 may be formed in astructure in which two or more color filters selected from the groupconsisting of a red color filter, a green color filter, a blue colorfilter, a cyan color filter, a magenta color filter, and a yellow colorfilter are stacked.

The color filters constituting the light cut-off filter layer 117 may beformed of an organic material. The organic material used for the colorfilter may be one material or a combination of two or more materialsselected from the group consisting of polyacetylene, poly(p-phenylene),polythiophene, poly(3,4-ethylenedioxy thiophene) (PEDOT), polypyrrole,poly(p-phenylene sulfide), poly(p-phenylene vinylene), and polyaniline.

Light generated from the OLED panel 210 may be reflected by a finger andbe incident on each of the pixels 110 of the image sensor 100. The lightpasses through the lens 116 and the planarization layer 115. The lightmay pass through the IR cut-off filter 114 and be incident on thephotodiode 112 via the opening 113 a formed in the light shield grid113. Light having a wavelength range corresponding to an IR range may becut-off by the IR cut-off filter 114.

Referring to FIG. 8B, the device isolation portion DTI having apredetermined depth may be disposed between the pixels 110. The darkcurrent suppression layer 111 may be disposed above the device isolationportion DTI and the photodiode 112. The IR cut-off filter 114 may bedisposed on the dark current suppression layer 111. The light shieldgrid 113 may be disposed on the IR cut-off filter 114. The light cut-offfilter layer 117 may be disposed on the light shield grid 113. Theplanarization layer 115 may be disposed on the light cut-off filterlayer 117. The lens 116 may be disposed on the planarization layer 115.

For example, the device isolation portion DTI may be formed in the backside of the silicon substrate, and the dark current suppression layer111 may be disposed above the device isolation portion DTI and thephotodiode 112.

The dark current suppression layer 111 may be formed on the front (orback) side of the silicon substrate. A voltage of 0 V to −2 V is appliedto the light shield grid 113, and the dark current suppression layer 111is disposed such that generation of a dark current from the photodiode112 may be prevented/impeded.

The dark current suppression layer 111 may be formed by stacking aplurality of layers, each of which have a fixed negative charge. Each ofthe plurality of layers constituting the dark current suppression layer111 may be formed of one material or a combination of two or morematerials selected from the group consisting of AlO, TaO, HfO, ZrO, andLaO.

For example, as shown in FIG. 3C, the dark current suppression layer 111and the device isolation portion DTI may be integrated and formed of aplurality of layers. When the dark current suppression layer 111 and thedevice isolation portion DTI are integrally formed, each of the darkcurrent suppression layer 111 and the device isolation portion DTI maybe formed by stacking a plurality of layers, each of which have a fixednegative charge. As shown in FIGS. 4A and 4B, the IR cut-off filter 114may be constituted of a plurality of layers formed by the plurality oflow refractive index films 114L having the same refractive index and theplurality of high refractive index films 114H having the same refractiveindex being alternately stacked.

As shown in FIGS. 4C and 4D, the IR cut-off filter 114 may beconstituted of a plurality of layers formed by the plurality of highrefractive index films 114H-1 to 114H-10 having different refractiveindexes and the plurality of low refractive index films 114L-1 to114L-10 having different refractive indexes being alternately stacked.

In order to prevent/impede reflection of light from the upper surface ofthe light shield grid 113, the light cut-off filter layer 117 may bedisposed in a form in which a red color filter, a green color filter,and a blue color filter are stacked.

The light cut-off filter layer 117 may be formed in a structure in whichtwo or more color filters selected from the group consisting of a redcolor filter, a green color filter, a blue color filter, a cyan colorfilter, a magenta color filter, and a yellow color filter are stacked.

FIG. 9A is a diagram illustrating the IR cut-off filter disposed at acentral portion of the planarization layer according to some exampleembodiments of the inventive concepts. FIG. 9B is a diagram illustratingthe dark current suppression layer disposed in the pixel 110 shown inFIG. 9A. In describing the pixel 110 shown in FIGS. 9A and 9B, adescription of a structure that is the same as that of the pixel 110shown in FIGS. 3A to 3C will be omitted.

Referring to FIGS. 1 and 9A, each of the plurality of pixels 110 mayinclude the photodiode 112, the light shield grid 113, the deviceisolation portion (e.g., device isolation region or device isolationfilm) DTI, the IR cut-off filter 114, the planarization layer 115, andthe lens 116.

The photodiode 112 may be formed on the back side of the siliconsubstrate. The transistors TX, RX, DX, and SX and the lines are formedon the front side of the silicon substrate. Then, the light shield grid113, the IR cut-off filter 114, the planarization layer 115, and thelens 116 may be disposed above the photodiode 112.

The device isolation portion DTI having a predetermined depth may bedisposed between the pixels 110. The device isolation portion DTI isconfigured to reduce interference between the pixels 110 and may bedisposed to surround each of the pixels 110. The device isolationportion DTI may be formed by forming a trench on the back side of thesilicon substrate and then filling the trench with an insulating film.The device isolation portion DTI may be formed to have a depth of 1 μmto 5 μm. The device isolation portion DTI may be formed as a deep trenchisolation layer including an insulating material. The device isolationportion DTI may be formed of an insulating material having a refractiveindex that is less than that of the silicon substrate, therebypreventing/impeding light incident on each of the pixels 110 frompassing over adjacent pixels 110. The device isolation portion DTI isdeeply formed in the silicon substrate such that light interferencebetween adjacent pixels 110 may be prevented/impeded.

The light shield grid 113 may be disposed above the photodiode 112. Theplanarization layer 115 and the IR cut-off filter 114 may be disposedabove the light shield grid 113. The lens 116 may be disposed on theplanarization layer 115.

The planarization layer 115 may be constituted of a first planarizationlayer 115 a and a second planarization layer 115 b. The IR cut-offfilter 114 may be disposed between the first planarization layer 115 aand the second planarization layer 115 b. The IR cut-off filter 114 maybe disposed in the middle of the planarization layer 115. The firstplanarization layer 115 a may be formed of a transparent material with apredetermined thickness during a manufacturing process. The IR cut-offfilter 114 may be formed on the first planarization layer 115 a. Thesecond planarization layer 115 b may be formed on the IR cut-off filter114 with a predetermined thickness. The lens 116 may be disposed on theplanarization layer 115.

The light shield grid 113 may be formed of a metal material such as W.The image sensor 100 of the inventive concepts is configured to generatea fingerprint image of a finger, and the opening 113 a of the lightshield grid 113 may be formed to be very small (see FIGS. 5A and 5B).

For example, the opening 113 a of the light shield grid 113 may beformed to correspond to an area of 1 to 15% of each of the pixels 110.An area of 1 to 15% of the pixel 110 is opened by the opening 113 a.Light may be incident on the photodiode 112 through the opening 113 a,which is formed to be smaller than the area of the pixel 110. Since theopening 113 a of the light shield grid 113 is formed to be very small,light may be accurately incident on the photodiode 112 without passingover adjacent pixels 110.

In order to suppress a dark current which may occur in the photodiode112, a voltage of 0 V to −2 V may be applied to the light shield grid113.

The IR cut-off filter 114 is configured to prevent/reduce aphotoelectric effect due to IRs out of a visible ray range and may bedisposed above the photodiode 112 and the light shield grid 113.

Light generated from the OLED panel 210 may be reflected by a finger andbe incident on each of the pixels 110 of the image sensor 100. The lightmay pass through the lens 116, the planarization layer 115, and the IRcut-off filter 114. The light may be incident on the photodiode 112 viathe opening 113 a formed by the light shield grid 113. Light having awavelength range corresponding to an IR range may be cut-off by the IRcut-off filter 114.

Referring to FIG. 9B, the device isolation portion DTI having apredetermined depth may be disposed between the pixels 110. The darkcurrent suppression layer 111 may be disposed above the device isolationportion DTI and the photodiode 112. The light shield grid 113 may bedisposed on the dark current suppression layer 111. The planarizationlayer 115 and the IR cut-off filter 114 may be disposed above the lightshield grid 113. The lens 116 may be disposed on the planarization layer115.

For example, the device isolation portion DTI may be formed in the backside of the silicon substrate, and the dark current suppression layer111 may be disposed above the device isolation portion DTI and thephotodiode 112.

The dark current suppression layer 111 may be formed on the front (orback) side of the silicon substrate. A voltage of 0 V to −2 V is appliedto the light shield grid 113 and the dark current suppression layer 111is disposed such that generation of a dark current from the photodiode112 may be prevented/impeded.

The dark current suppression layer 111 may be formed by stacking aplurality of layers, each of which have a fixed negative charge. Each ofthe plurality of layers constituting the dark current suppression layer111 may be formed of one material or a combination of two or morematerials selected from the group consisting of AlO, TaO, HfO, ZrO, andLaO.

For example, as shown in FIG. 3C, the dark current suppression layer 111and the device isolation portion DTI may be collectively integrated andformed of a plurality of layers. When the dark current suppression layer111 and the device isolation portion DTI are integrally formed, each ofthe dark current suppression layer 111 and the device isolation portionDTI may be formed by stacking a plurality of layers, each of which havea fixed negative charge.

As shown in FIGS. 4A and 4B, the IR cut-off filter 114 may beconstituted of a plurality of layers formed by the plurality of lowrefractive index films 114L having the same refractive index and theplurality of high refractive index films 114H having the same refractiveindex being alternately stacked.

As shown in FIGS. 4C and 4D, the IR cut-off filter 114 may beconstituted of a plurality of layers formed by the plurality of highrefractive index films 114H-1 to 114H-10 having different refractiveindexes and the plurality of low refractive index films 114L-1 to114L-10 having different refractive indexes being alternately stacked.

FIG. 10A is a diagram illustrating the IR cut-off filter disposed on theplanarization layer according to some example embodiments of theinventive concepts. FIG. 10B is a diagram illustrating the dark currentsuppression layer disposed in the pixel 110 shown in FIG. 10A. Indescribing the pixel 110 shown in FIGS. 10A and 10B, a description of astructure that is the same as that of the pixel 110 shown in FIGS. 3A to3C will be omitted.

Referring to FIGS. 1 and 10A, each of the plurality of pixels 110 mayinclude the photodiode 112, the light shield grid 113, the deviceisolation portion (e.g., device isolation region or device isolationfilm) DTI, planarization layer 115, the IR cut-off filter 114, and thelens 116.

The photodiode 112 may be formed on the back side of the siliconsubstrate. The transistors TX, RX, DX, and SX and the lines are formedon the front side of the silicon substrate. Then, the light shield grid113, the IR cut-off filter 114, the planarization layer 115, and thelens 116 may be disposed above the photodiode 112.

The device isolation portion DTI having a predetermined depth may bedisposed between the pixels 110. The device isolation portion DTI isconfigured to reduce interference between the pixels 110 and may bedisposed to surround each of the pixels 110. The device isolationportion DTI may be formed by forming a trench on the back side of thesilicon substrate and then filling the trench with an insulating film.The device isolation portion DTI may be formed to have a depth of 1 μmto 5 μm. The device isolation portion DTI may be formed as a deep trenchisolation layer including an insulating material. The device isolationportion DTI may be formed of an insulating material having a refractiveindex that is less than that of the silicon substrate, therebypreventing/impeding light incident on each of the pixels 110 frompassing over adjacent pixels 110. The device isolation portion DTI isdeeply formed in the silicon substrate such that light interferencebetween adjacent pixels 110 may be prevented/impeded.

The light shield grid 113 may be disposed above the photodiode 112. Theplanarization layer 115 may be disposed on the light shield grid 113.The IR cut-off filter 114 may be disposed on the planarization layer115. The lens 116 may be disposed on the IR cut-off filter 114.

The light shield grid 113 may be formed of a metal material such as W.The image sensor 100 of the inventive concepts is configured to generatea fingerprint image of a finger, and the opening 113 a of the lightshield grid 113 may be formed to be very small (see FIGS. 5A and 5B).

For example, the opening 113 a of the light shield grid 113 may beformed to correspond to an area of 1 to 15% of each of the pixels 110.An area of 1 to 15% of the pixel 110 is opened by the opening 113 a.Light may be incident on the photodiode 112 through the opening 113 a,which is formed to be smaller than the area of the pixel 110. Since theopening 113 a of the light shield grid 113 is formed to be very small,light may be accurately incident on the photodiode 112 without passingover adjacent pixels 110.

In order to suppress a dark current which may occur in the photodiode112, a voltage of 0 V to −2 V may be applied to the light shield grid113.

The IR cut-off filter 114 is configured to prevent/reduce aphotoelectric effect due to IRs out of a visible ray range and may bedisposed on the planarization layer 115.

Light generated from the OLED panel 210 may be reflected by a finger andbe incident on each of the pixels 110 of the image sensor 100. The lightmay pass through the lens 116, the IR cut-off filter 114, and theplanarization layer 115. The light may be incident on the photodiode 112via the opening 113 a formed in the light shield grid 113. Light havinga wavelength range corresponding to an IR range may be cut-off by the IRcut-off filter 114.

Referring to FIG. 10B, the device isolation portion DTI having apredetermined depth may be disposed between the pixels 110. The darkcurrent suppression layer 111 may be disposed above the device isolationportion DTI and the photodiode 112. The light shield grid 113 may bedisposed on the dark current suppression layer 111. The planarizationlayer 115 may be disposed on the light shield grid 113. The IR cut-offfilter 114 may be disposed on the planarization layer 115. The lens 116may be disposed on the IR cut-off filter 114.

For example, the device isolation portion DTI may be formed in the backside of the silicon substrate, and the dark current suppression layer111 may be disposed above the device isolation portion DTI and thephotodiode 112. A voltage of 0 V to −2 V is applied to the light shieldgrid 113, and the dark current suppression layer 111 is disposed suchthat generation of a dark current from the photodiode 112 may beprevented/impeded.

The dark current suppression layer 111 may be formed by stacking aplurality of layers, each of which have a fixed negative charge. Each ofthe plurality of layers constituting the dark current suppression layer111 may be formed of one material or a combination of two or morematerials selected from the group consisting of AlO, TaO, HfO, ZrO, andLaO.

For example, as shown in FIG. 3C, the dark current suppression layer 111and the device isolation portion DTI may be integrated and formed of aplurality of layers. When the dark current suppression layer 111 and thedevice isolation portion DTI are integrally formed, each of the darkcurrent suppression layer 111 and the device isolation portion DTI maybe formed by stacking a plurality of layers, each of which have a fixednegative charge.

As shown in FIGS. 4A and 4B, the IR cut-off filter 114 may beconstituted of a plurality of layers formed by the plurality of lowrefractive index films 114L having the same refractive index and theplurality of high refractive index films 114H having the same refractiveindex being alternately stacked.

As shown in FIGS. 4C and 4D, the IR cut-off filter 114 may beconstituted of a plurality of layers formed by the plurality of highrefractive index films 114H-1 to 114H-10 having different refractiveindexes and the plurality of low refractive index films 114L-1 to114L-10 having different refractive indexes being alternately stacked.

FIG. 11A is a diagram illustrating the IR cut-off filter disposed on thelens according to some example embodiments of the inventive concepts.FIG. 11B is a diagram illustrating the dark current suppression layerdisposed in the pixel 110 shown in FIG. 11A. In describing the pixel 110shown in FIGS. 11A and 11B, a description of a structure that is thesame as that of the pixel 110 shown in FIGS. 3A to 3C will be omitted.

Referring to FIGS. 1 and 11A, each of the plurality of pixels 110 mayinclude the photodiode 112, the light shield grid 113, the deviceisolation portion (e.g., device isolation region or device isolationfilm) DTI, the planarization layer 115, the lens 116, and the IR cut-offfilter 114.

The photodiode 112 may be formed on the back side of the siliconsubstrate. The transistors TX, RX, DX, and SX and the lines are formedon the front side of the silicon substrate. Then, the light shield grid113, the planarization layer 115, the lens 116, and the IR cut-offfilter 114 may be disposed above the photodiode 112.

The device isolation portion DTI having a predetermined depth may bedisposed between the pixels 110. The device isolation portion DTI isconfigured to reduce interference between the pixels 110 and may bedisposed to surround each of the pixels 110. The device isolationportion DTI may be formed by forming a trench on the back side of thesilicon substrate and then filling the trench with an insulating film.The device isolation portion DTI may be formed to have a depth of 1 μmto 5 μm. The device isolation portion DTI may be formed as a deep trenchisolation layer including an insulating material. The device isolationportion DTI may be formed of an insulating material having a refractiveindex that is less than that of the silicon substrate, therebypreventing/impeding light incident on each of the pixels 110 frompassing over adjacent pixels 110. The device isolation portion DTI isdeeply formed in the silicon substrate such that light interferencebetween adjacent pixels 110 may be prevented/impeded.

The light shield grid 113 may be disposed above the photodiode 112. Theplanarization layer 115 may be disposed on the light shield grid 113.The lens 116 may be disposed on the planarization layer 115. The IRcut-off filter 114 may be disposed on the lens 116. The IR cut-offfilter 114 may be disposed between the lens 116 and the OLED panel 210.

The light shield grid 113 may be formed of a metal material such as W.The image sensor 100 of the inventive concepts is configured to generatea fingerprint image of a finger, and the opening 113 a of the lightshield grid 113 may be formed to be very small (see FIGS. 5A and 5B).

For example, the opening 113 a of the light shield grid 113 may beformed to correspond to an area of 1 to 15% of each of the pixels 110.An area of 1 to 15% of the pixel 110 is opened by the opening 113 a.Light may be incident on the photodiode 112 through the opening 113 a,which is formed to be smaller than the area of the pixel 110. Since theopening 113 a of the light shield grid 113 is formed to be very small,light may be accurately incident on the photodiode 112 without passingover adjacent pixels 110.

In order to suppress a dark current which may occur in the photodiode112, a voltage of 0 V to −2 V may be applied to the light shield grid113.

The IR cut-off filter 114 is configured to prevent/reduce aphotoelectric effect due to IRs out of a visible ray range and may bedisposed on the planarization layer 115.

Light generated from the OLED panel 210 may be reflected by a finger andbe incident on each of the pixels 110 of the image sensor 100. The lightmay pass through the lens 116, the IR cut-off filter 114, and theplanarization layer 115. The light may be incident on the photodiode 112via the opening 113 a formed in the light shield grid 113. Light havinga wavelength range corresponding to an IR range may be cut-off by the IRcut-off filter 114.

Referring to FIG. 11B, the device isolation portion DTI having apredetermined depth may be disposed between the pixels 110. The darkcurrent suppression layer 111 may be disposed above the device isolationportion DTI and the photodiode 112. The light shield grid 113 may bedisposed on the dark current suppression layer 111. The planarizationlayer 115 may be disposed on the light shield grid 113. The lens 116 maybe disposed on the planarization layer 115. The IR cut-off filter 114may be disposed on the lens 116.

For example, the device isolation portion DTI may be formed in the backside of the silicon substrate, and the dark current suppression layer111 may be disposed above the device isolation portion DTI and thephotodiode 112. The dark current suppression layer 111 may be integrallyformed with the device isolation portion DTI. The dark currentsuppression layer 111 may be formed on the front (or back) side of thesilicon substrate. A voltage of 0 V to −2 V is applied to the lightshield grid 113 and the dark current suppression layer 111 is disposedsuch that generation of a dark current from the photodiode 112 may beprevented/impeded.

The dark current suppression layer 111 may be formed by stacking aplurality of layers, each of which have a fixed negative charge. Each ofthe plurality of layers constituting the dark current suppression layer111 may be formed of one material or a combination of two or morematerials selected from the group consisting of AlO, TaO, HfO, ZrO, andLaO.

For example, as shown in FIG. 3C, the dark current suppression layer 111and the device isolation portion DTI may be integrated and formed of aplurality of layers. When the dark current suppression layer 111 and thedevice isolation portion DTI are integrally formed, each of the darkcurrent suppression layer 111 and the device isolation portion DTI maybe formed by stacking a plurality of layers, each of which have a fixednegative charge.

As shown in FIGS. 4A and 4B, the IR cut-off filter 114 may beconstituted of a plurality of layers formed by the plurality of lowrefractive index films 114L having the same refractive index and theplurality of high refractive index films 114H having the same refractiveindex being alternately stacked.

As shown in FIGS. 4C and 4D, the IR cut-off filter 114 may beconstituted of a plurality of layers formed by the plurality of highrefractive index films 114H-1 to 114H-10 having different refractiveindexes and the plurality of low refractive index films 114L-1 to114L-10 having different refractive indexes being alternately stacked.

With reference to FIGS. 1 to 11B, it has been described that the IRcut-off filter 114 is incorporated into (i.e., is built-in rather thanseparate from) the BSI image sensor 100. The inventive concepts are notlimited thereto, and the IR cut-off filter 114 of the inventive conceptsmay be incorporated into a front side illumination (FSI) image sensor.In addition to incorporating the IR cut-off filter 114 into the FSIimage sensor, the light shield grid 113 and the light cut-off filterlayer 117 of the inventive concepts may be applied to the FSI imagesensor. Even in the FSI image sensor, the device isolation portion DTIand the dark current suppression layer 111 of the inventive concepts maybe applied thereto. In the FSI image sensor, the dark currentsuppression layer 111 and the device isolation portion DTI may beintegrated and formed of a plurality of layers. When the dark currentsuppression layer 111 and the device isolation portion DTI areintegrally formed, each of the dark current suppression layer 111 andthe device isolation portion DTI may be formed by stacking a pluralityof layers, each of which have a fixed negative charge.

FIG. 12 is a diagram showing image degradation by comparing a case inwhich an IR cut-off filter is embedded in an image sensor with a case inwhich the IR cut-off filter is not applied to the image sensor.

Referring to FIG. 12, it can be seen that the image sensor to which theIR cut-off filter is not applied causes degradation in a fingerprintimage because IRs are incident on a photodiode. Even through a usertouches a screen of an electronic device, an error occurs in recognizinga fingerprint due to degradation of the fingerprint image

According to some example embodiments of the inventive concepts, animage sensor incorporating an IR cut-off filter can reduce degradationof a sensed fingerprint image. It is possible to generate ahigh-resolution fingerprint image through the image sensor such thatperformance of fingerprint recognition can be improved when a usertouches a screen of an electronic device.

In the electronic device 10 according to some example embodiments of theinventive concepts, since the image sensor is disposed below the screenon which an image is displayed, it is not necessary to dispose aseparate fingerprint sensor on a rim or a back side of the electronicdevice. In addition, according to some example embodiments of theinventive concepts, manufacturing efficiency of an image sensor modulecan be improved by incorporating the IR cut-off filter into the imagesensor. Further, according to some example embodiments of the inventiveconcepts, a thickness and a manufacturing cost of the image sensormodule can be reduced by incorporating the IR cut-off filter into theimage sensor. Furthermore, according to some example embodiments of theinventive concepts, the image sensor incorporating the IR cut-off filteris applied to a cellular phone such that a thickness of the cellularphone can be reduced and a degree of design freedom in designing thecellular phone can be increased.

Additionally, according to some example embodiments of the inventiveconcepts, a BSI image sensor incorporating an IR cut-off filter can beprovided.

According to some example embodiments of the inventive concepts,manufacturing efficiency of an image sensor module can be improved byincorporating the IR cut-off filter into the BSI image sensor.

Further, according to some example embodiments of the inventiveconcepts, a thickness and a manufacturing cost of the image sensormodule can be reduced by incorporating the IR cut-off filter into theBSI image sensor.

Furthermore, according to some example embodiments of the inventiveconcepts, an electronic device including the BSI image sensorincorporating the IR cut-off filter can be provided.

Additionally, according to some example embodiments of the inventiveconcepts, the BSI image sensor incorporating the IR cut-off filter isapplied to a cellular phone such that a thickness of the cellular phonecan be reduced.

Further, according to some example embodiments of the inventiveconcepts, the BSI image sensor incorporating the IR cut-off filter isapplied to the cellular phone such that a degree of design freedom indesigning the cellular phone can be increased.

Though some example embodiments of the inventive concepts have beendescribed with reference to the accompanying drawings, it will beunderstood by those skilled in the art that various modifications may bemade without departing from the scope of the inventive concepts.Therefore, the above-described example embodiments should be consideredin a descriptive sense only and not for purposes of limitation.

What is claimed is:
 1. An image sensor comprising: a substrate; aphotodiode in the substrate; a first opening above the photodiode; aninfrared ray (IR) cut-off filter layer disposed above the first opening;a light cut-off filter layer formed above the IR cut-off filter layer,wherein the light cut-off filter layer includes a second opening; aplanarization layer disposed above the light cut-off filter layer; and alens corresponding to the photodiode; wherein the second opening isvertically aligned with the first opening, wherein the IR cut-off filtercomprises a plurality of layers and any one of the plurality of layershas a refractive index in a range of 1.2 to 1.8.
 2. The image sensor ofclaim 1, wherein the first opening is circular.
 3. The image sensor ofclaim 2, wherein the first opening is vertically aligned with a centralportion of the photodiode.
 4. The image sensor of claim 3, wherein theplanarization layer is formed of a single film.
 5. The image sensor ofclaim 3, wherein the planarization layer is formed of two or morestacked film.
 6. The image sensor of claim 3, wherein the IR cut-offfilter layer comprises a low refractive index film and a high refractiveindex film.
 7. The image sensor of claim 6, wherein the IR cut-offfilter layer comprises a plurality of high refractive index films. 8.The image sensor of claim 7, wherein the IR cut-off filter layercomprises a plurality of low refractive index films.
 9. The image sensorof claim 8, wherein the plurality of low refractive index films and theplurality of high refractive index films are alternately stacked.
 10. Animage sensor comprising: a substrate; and a plurality of pixelsconfigured to generate electrical signals responsive to light, whereineach of the plurality of pixels comprises: a photodiode; a first openingabove the photodiode; an infrared radiation (IR) cut-off filter layerdisposed above the first opening; a light cut-off filter layer disposedabove the IR cut-off filter layer, wherein the light cut-off filterlayer includes a second opening; a planarization layer disposed abovethe light cut-off filter layer; and a lens disposed above theplanarization layer; wherein the second opening is vertically alignedwith the first opening, wherein a vertical projection of the firstopening corresponds to 1 to 15% of an area of each of the plurality ofpixels.
 11. The image sensor of claim 10, wherein the first opening iscircular.
 12. The image sensor of claim 11, wherein the first opening isvertically aligned with a central portion of the photodiode.
 13. Theimage sensor of claim 12, wherein the planarization layer is formed of asingle film.
 14. The image sensor of claim 12, wherein the planarizationlayer is formed of two or more stacked film.
 15. The image sensor ofclaim 12, wherein the IR cut-off filter layer comprises a plurality oflayers.
 16. The image sensor of claim 15, wherein the IR cut-off filterlayer has a low refractive index film and a high refractive index film.17. An image sensor comprising: a substrate; and a plurality of pixelsconfigured to generate electrical signals responsive to light, whereineach of the plurality of pixels comprises: a photodiode; a first openingabove the photodiode; an infrared radiation (IR) cut-off filter layerdisposed above the first opening; a light cut-off filter layer disposedabove the IR cut-off filter layer, wherein the light cut-off filterlayer includes a second opening; a planarization layer disposed abovethe light cut-off filter layer; and a lens disposed above theplanarization layer; wherein the second opening is vertically alignedwith the first opening, wherein the IR cut-off filter layer comprises aplurality of layers and the plurality of layers are formed withdifferent thicknesses.
 18. The image sensor of claim 17, wherein the IRcut-off filter layer comprises a plurality of low refractive index filmsand a plurality of high refractive index films.
 19. The image sensor ofclaim 17, wherein the first opening is circular.
 20. The image sensor ofclaim 19, wherein the plurality of high refractive index films have anyone refractive index in a range of 2.0 to 2.8.